1. Field of the Invention
The present invention relates to a liquid supply apparatus, more particularly to a portable liquid supply apparatus that is constructed so that liquid medicine, etc. is supplied in a constant quantity per unit time.
2. Description of the Related Art
There are a number of cases where certain kinds of medicine should be injected into a patient in a constant quantity per unit time and over a long period of time. The example of the medicine is an anodyne that is dosed to a patient feeling serious pain. Unless the anodyne is dosed to a patient in a constant quantity per unit time, the patient may feel pain.
An apparatus for injecting such a medicine by pushing, in a constant speed, a plunger of a common syringe mounted to the apparatus, is known. It is unsuitable for a patient to carry the conventional apparatus due to its large size.
A kind of a medicine injection apparatus capable of being carried by a patient is currently being used. The portable medicine injection apparatus is a structure in which a resilient bladder made of rubber material is provided in a cylindrical chamber. An inlet and an outlet are formed on the resilient bladder. The bladder inflates as the medicine is injected thereinto through the inlet. A small tube is attached to the outlet through which the medicine gradually draws off. The medicine (an injection) is discharged in a small amount and injected in droplet form at a site, such as a vein or an epidural space of a patient, where a medical doctor targets.
In a medicine injection apparatus using its resiliency, the resilient bladder may cause some problems. Inferior goods, in which thickness of the bladder is not uniform and fine holes are formed thereon, may be manufactured. The inferiority affects the resiliency of the bladder which, in turn, cannot have the desired resiliency. If this is the case, it is impossible to dose the medicine to the patient in a constant quantity per unit time. Furthermore, a medical doctor cannot beforehand treat the inferiority since it is usually discovered during the use of the bladder.
A medicine injection apparatus using a bladder and an elastic body is proposed. The resilient bladder or elastic body has such a problem that its resiliency or elasticity may be varied in accordance with the quantity of the medicine contained therein. There is also the following shortcoming. That is, the medicine is injected into the bladder or body in an excessively larger quantity than the doctor targets since an external force (elasticity of the elastic body) affecting on a liquid flow is too large at an early period of the injection, whereas the medicine is injected in an amount much smaller than the target at a late period of the injection since the external force is too small.
Therefore, various functions are required when the liquid supply apparatus is especially used for the medicine injection apparatus. First of all, the function of maintaining a constant medicine injection quantity per unit time is required. It is preferred that variation of the medicine injection quantity per unit time be minimized. Portability makes the apparatus convenient. Further, it is preferred that the medicine injection apparatus be constructed to have low possibility of inferiority occurrence in the parts.
It is preferred that the medicine injection apparatus be capable of setting an injection quantity per unit time (hereinafter, referred to as xe2x80x9cinjection speedxe2x80x9d). It is more preferred that the apparatus be constructed to permit possibility of arbitrary changes of the setting by a user (a patient) to be limited after once setting the injection quantity per unit time. The reason is that in general, the medicine such as an anodyne should be injected in a constant quantity, and the injection quantity of the medicine should be predetermined and injected under supervision of the doctor. Further, the patient should not be able to adjust the injection quantity of the medicine. Therefore, a locking function is required for preventing the patient from changing the injection quantity per unit time, at least after it is set, pursuant to the doctor""s instructions and under his supervision. Nevertheless, the patient can increase the injection quantity per unit time to an extent within a specific range that had been set by the doctor. The reason is why the medicine injection quantity can be increased within a limited range if the patient""s pain is getting serious.
It is also preferred that the medicine injection apparatus be constructed to interrupt the medicine injection by automatically detecting whether the medicine is not further injected. The reason is that it is required to cope with the problems when an injection syringe gets removed, when the patient is subjected to an intravenous injection.
In addition to these characteristics, it is still preferred that the medicine injection apparatus be constructed so as to minimize the possibility of introduction of air into the patient""s body together with the medicine when the medicine is injected to the patient. Minimization of leakage during the injection should also be considered.
An aspect of the present invention provides a liquid supply apparatus. The liquid supply apparatus comprises: a cylinder having an interior space, a head portion and a rear portion, the head portion having a liquid-flow opening; a piston located in the interior space of the cylinder and air-tightly partitioning the interior space into a liquid compartment on the side of head portion and a gas compartment on the side of the rear portion; a gas supply apparatus configured to be coupled to the rear portion and to supply a gas into the gas compartment; and wherein the piston is configured to move toward the head portion when the gas is supplied to the gas compartment.
In the liquid supply apparatus, the gas supply apparatus comprises a solid material and a liquid material capable of generating the gas by a chemical reaction thereof. The solid material contains a metal carbonate. The solid material comprises 70-95 wt % of sodium bicarbonate (NaHCO3), 3-30 wt % of gelatin, and no more than 3 wt % of talc. The solid material comprises 90-94 wt % of sodium bicarbonate (NaHCO3), 5-10 wt % of gelatin, and no more than 1 wt % of talc. The liquid material is a solution of L-tartaric acid (C4H6O6). The gas supply apparatus is configured to generate the gas at a pressure from about 0.35 kg/cm2 to about 0.50 kg/cm2.
In the liquid supply apparatus, the gas supply apparatus comprises: a first material; a second material; a breakable partition isolating the first and second materials from each other; a reaction vessel where the first and second materials react with each other when the partition is broken; and a partition breaker configured to break the breakable partition so as to let the first and second material contact each other in the reaction vessel. Either of the first and second materials is a liquid, and the reaction vessel is a container containing the liquid. The gas supply apparatus further comprises a gas collecting structure comprising a liquid-impermeable-but-gas-permeable sheet arranged to contact the liquid. The liquid-impermeable-but-gas-permeable sheet is placed on a wall of the reaction vessel such that at least a portion of the sheet is exposed to the gas generated from the reaction. The gas collecting structure further comprises a gas-passage sheet and a liquid-and-gas-impermeable sheet, and wherein the gas-passage sheet is located between the liquid-impermeable-but-gas-permeable sheet and the liquid-and-gas-impermeable sheet. The gas-passage sheet is made of non-woven fabric or foam material. The gas supply apparatus further comprises a gas pressure regulator configured to control or regulate the pressure of the gas supplied into the gas compartment.
Still in the liquid supply apparatus, the head portion of the cylinder comprises a projection extending into the interior space and has a longitudinal through-hole, the through-hole constituting the liquid-flow opening. The piston has a leading end facing the projection, wherein the piston has a recess on the leading end thereof, and wherein the recess is configured to receive the projection. The recess is further configured to substantially contact with the projection when receiving the projection. The liquid supply apparatus further comprises a tube connected to the cylinder via the through-hole of the projection, wherein the tube is in fluid communication with the liquid compartment. The liquid supply apparatus further comprises a cap configured to cover a distal end of the tube, the cap having a through-hole in fluid communication with the tube, the cap further comprising a gas-permeable-but-liquid-impermeable material located between the through-hole and the distal end of the tube. The piston has a recess on a trailing end thereof.
Another aspect of the present invention provides a method of continuously supplying a liquid for an extended period of time. The method comprises: providing the liquid supply apparatus of Claim 1; filling the liquid compartment with a liquid; activating the gas supply apparatus so as to supply the gas into the gas compartment, wherein the gas supply apparatus continuously supplies the gas into the gas compartment for an extended period of time; and wherein the piston is moved toward the head portion as a gaseous pressure within the gas compartment increases, whereby the liquid in the liquid compartment flows out of the liquid compartment through the liquid-flow opening. In the method, the liquid is a liquid medication.
Still another aspect of the present invention provides a liquid supply apparatus. The apparatus comprises: a cylinder having a head portion and an interior space, wherein the head portion of the cylinder has a projection extending into the interior space and a longitudinal through-hole in the projection; a piston located in the interior space of the cylinder and air-tightly partitioning the interior space into two compartments; and wherein the piston has a leading end facing the projection and a recess on the leading end thereof, the recess being configured to receive the projection. The recess is further configured to substantially contact with the projection when receiving the projection. The liquid supply apparatus further comprises a tube connected to the cylinder via the through-hole of the projection, wherein the tube is in fluid communication with the liquid compartment. The piston has a recess on a trailing end thereof. The piston comprises a cylindrical body and a sealing ring, wherein the cylindrical body has an annular groove on an outer surface thereof, and wherein the sealing ring is fitted around the groove.
A further aspect of the present invention provides a cap for covering a liquid supply tube. The cap comprises: a cap body configured to receive an end of a liquid supply tube; a through-hole formed on the cap body, the through-hole being in fluid communication with the liquid supply tube; a gas-permeable-but-liquid-impermeable material located between the through-hole and the distal end of the tube; and wherein the material allows passage of a gas from the tube through the through-hole while preventing passage of a liquid through the through-hole. The cap body is configured to tightly receive the end of the liquid supply tube.
According to an aspect of the present invention, the liquid supply apparatus that is capable of injecting the liquid in a constant injection speed over a long time period is provided.
According to an aspect of the present invention, there is provided a liquid supply apparatus comprising an elongated cylinder provided with an outlet at a front head portion thereof, a piston inserted into the cylinder for moving along the length of the cylinder and pushing out liquid within the cylinder through the outlet, and a piston pushing apparatus mounted on an opened rear portion of the cylinder for pushing the piston toward the head portion at a generally constant speed, wherein the piston pushing apparatus includes a moving member for contacting a rear portion of the piston and moving linearly within the cylinder, a driving motor, and a movement transferring mechanism for transferring the drive of the driving motor to the moving member.
According to another aspect of the present invention, there is provided a liquid supply apparatus comprising an elongated cylinder provided with an outlet at a front head portion thereof, and a piston inserted into the cylinder for moving along the length of the cylinder and pushing out liquid within the cylinder through the outlet, wherein the head portion of the cylinder is formed with a projection extending therefrom toward the interior of the cylinder, the outlet of the head portion is formed by providing the projection with a longitudinal through-hole, and a leading end of the piston is provided with a recess for receiving the projection.
According to a further aspect of the present invention, there is provided a liquid supply apparatus comprising an elongated cylinder provided with an outlet at a front head portion thereof, a piston inserted into the cylinder for moving along the length of the cylinder and pushing out liquid within the cylinder through the outlet, and a piston pushing apparatus mounted on an opened rear portion of the cylinder for pushing the piston toward the head portion, wherein the piston pushing apparatus includes a gas supply apparatus for supplying gas to a portion of the cylinder behind the piston so as to push the piston, wherein the gas supply apparatus comprises a first chamber for accommodating one of solid and liquid materials that can generate gas by a mutual chemical reaction, a second chamber for accommodating the other of the solid and liquid materials, a gas passage connected to the second chamber, and a liquid-impermeable but gas-permeable filter disposed in the second chamber or the gas passage. The second chamber is separated from the first chamber but is able to communicate with the first chamber by a user""s operation.